This instructable shows how to design a remotely controlled two-wheeled robotic rover over a wi-fi network, using an Arduino Uno connected to an ESP8266 Wi-fi module and two stepper motors. The robot can be controlled from an ordinary internet browser, using a HTML designed interface. An Android smartphone is used to broadcast video and audio from the robot to operator's control interface.

There is a lot of robotic kits available online with various shapes, dimensions and prices. But, depending on your application, none of them will fit, and you might find out they are too expensive for your experiments. Or maybe you just want to make your your mechanical structure instead of buying a complete one.This instructable also shows how to design and build a low-cost acrylic frame for your own robotic project, using just ordinary tools for those who doesn't have access to those expensive 3D printers or laser cutters. A simple robotic platform is presented.

This guide might be adapted to have its shape or control interface changed. It was adapted for other of my robotic projects ("Robô da Alegria"), that you can check in the links bellow:

Step 2: Mechanical Structure and Materials

To build a custom robot, first you'll have to design your mechanical structure. It might be easy, depending on your application, or full of details and constraints. You might need to design it in a 3D CAD software or just draw it in 2D, depending on the complexity of your model.

You might also buy the complete structure online if you doesn't want to build your own mechanical structure. There is a lot of robotic kits available online. In this case, you might jump to Step 6.

For this instructable, a low-cost acrylic frame was designed for the attachment of the motors and other components. The structure presented in this tutorial was 3D designed using 123D Design CAD software. Each part was later converted in 2D using Draftsight software.

The following materials were used:

2mm acrylic sheet

42x19mm wheels with rubber tread tire (x2)

49x20x32mm steel ball omni wheel (x1)

M2 x 10mm bolts (x12)

M2 x 1,5mm nuts (x12)

M3 x 10mm bolts (x8)

M3 x 1,5mm nuts (x8)

5/32" x 1" bolts (x3)

5/32" nuts (x6)

Handheld selfie stick clip

3 x 3 cm aluminum bracket (x4)

The construction of the structure of the base is divided in the following steps:

Cut the acrylic base according to the dimensions in the 2D drawing;

Drill the holes in the positions in shown in the 2D drawing;

Mount the components with bolts and nuts according to the 3D drawing.

Unfortunately the diameter of the stepper motor shaft is greater than the orifice on the wheel. So you'll probably need to use glue to couple those components. For this tutorial I improvised a wood coupling between the motor shaft and the wheel.

Step 3: Cutting the Structure

First you'll need to transfer the dimensions of your model to the acrylic sheet. Print your 2D drawing using an ordinary printer on an adhesive paper, then cut the paper in suitable dimensions and apply that mask on the surface of the acrylic.

You might use a hand saw to cut the acrylic according to your dimensions or use break technic described bellow.

With an utility knife and with the help of a ruler or a scale, cut the acrylic in straight lines. You won't need to cut all the way thru the sheet, just score it to create some tracks where the piece will be later cutted.

Place the acrylic on a flat surface, hold it in place with some clamps and apply some pressure until the sheet breaks into two. Repeat this process untill all the cuts are done. After that, you might use a sandpaper to smooth rough edges.

Step 4: Drilling the Base

Drill the holes in the positions in shown in the 2D drawing (indicated in the mask) with a drilling machine.

Acrylic is relativelly easy to drill. So if you don't dispose of a drilling machine, you can drill the holes manually with a sharp tool, like an utility knife. You might also use it to enlarge small holes to fit bolts sizes.

You won't need specific tools for the assembly of the circuit. All the components can be found online on your favourite e-commerce store. The circuit is powered by a power bank connected to Arduino's USB port.

Connect all the componets according to the schematic. You'll need some jumper wires to connect the ESP-8266 module and the stepper motors. You might use a protoshield (for a more compact circuit), an ordinary breadboard, or design you own Arduino shield.Plug the USB cable to the Arduino Uno board and proceed to the next step.

Step 7: Arduino Code

Install the latest Arduino IDE. In this project stepper.h library was used for the control of the stepper motors. No additional library was needed for communication with ESP-8266 module. Please check the baudrate of you ESP8266 and set it properly in the code.

Step 11: Usage

When the Arduino is restarted, it will try to connect your wi-fi network automatically. Use the Serial Monitor to check if the connection was successfull, and to obtain which IP was assigned to your ESP-8266 by your router. Open the html file in an internet browser (Firefox) and inform this IP address in the textbox.

You might also user other means to find out which IP address you router assigned to your device.

Disconnect the the Arduino Uno from your computer and connect it to the power bank. Wait for it to connect again.

Launch IP Webcam app in the smartphone attached to the robot. Type the video/audio IP on your control interface and connect to the server and you'll be ready to go. You might need to reduce the resolution of the video in the app to reduce the delay between during the transmission.

Click and hold the arrow buttons of your keyboar to rotate the robot or move it forward/backward and have fun exploring your environment.

After uploading the code to the Arduino, open the Serial Monitor. The Arduino will restart and automatically try to connect you wi-fi router (given by its SSID and password). If it connects successfully, the IP address will be shown.

Yes, you can use DC motors with an H-bridge instead of the stepper motors. This way your robot will move faster!Notice that sometimes the DC motors have different dynamics. This way, on motor might move faster than the other, and you might face some problems when you try to run on a straight line. Some position feedback of the wheels may be used.

I didn't have this error. Maybe it's because I'm using an older version of Arduino IDE.I searched on some forums, and it was suggested to cast the strings as char*. This way, you'll have to replace the following parts of the code:

Hi there! The ideia is to connect both the ESP8266 and the computer to the same router. This way, if you know the IP address given by the router to your ESP module, you can send messages from your computer directly to that IP address.

First let me say that this project is both cool and impressive. That said it seems overkill from a hardware standpoint. I've built plenty of projects this way myself. It starts out with me having X pieces of cool hardware in front of me and me thinking "Hmmm...what cool thing can I do with _all_ this stuff?"The parts on hand drive the design rather than the usual design driving the parts. The reason I mention this is that there are several levels of simplification that could be done here. For readers that want to experiment with a simplified version of this project, here are the levels of simplification that I see. you might find even more.

- Eliminate the Arduino and use the ESP8266 for everything. The ESP8266 can do most of what an Arduino can do and can even be programed from the Arduino IDE. Ordering a model that comes on a breakout board will let you connect all the I/O and motor control etc.

- Eliminate the ESP8266 and use the phone for everything. With an Android I/O bridge like the IOIO device, you can use the phone for everything, including the motor control. This however puts the code portion of the project into a whole other difficulty level as you'll be moving to coding on Android instead of the simple to code Arduino. You might however overcome some of this difficulty by exploring alternatives like BASIC! for Android which should give you a compromise between power and simplicity.

Thanks for your considerations! I really appreciated your advices, and agree on everything you said. Regarding the hardware, there is something I'd like to use in my defense. :DThis Instructable was derived from other project I'm part of: Joy Robot (https://hackaday.io/project/12873-rob-da-alegria-joy-robot or https://www.hackster.io/igorF2/robo-da-alegria-joy-robot-85e178). So I used the same hardware for simplicity.In that robot we use stepper motors because we don't need to move the body fast. They are only used to rotate it left/right and move slowly. We also want to hold the position, without any complex control.The Arduino Uno was used because it's very accessible and easy to use for everyone, and we wanted to design a simple shield for it. It also controls some servos and LED matrices, and interfaces with the ESP.The smartphone is actually replaced by a tablet, that runs other applications as well.Maybe I can use your sugestions later on other tutorial with your help! :D

Just to be clear, I wasn't trying to be negative on your project at all. I think it's awesome. I just know that everyone's build goes the way it does for reasons not always apparent to others. Like for example, using what you have on hand, or as part of one stage of a larger project etc. Because I realized that this was the case with your project, I just wanted to brainstorm a few options for those that may not have all the parts in the project, or have different parts on hand. As they say, there's always more than one way to do anything.

Thanks for the reply and I look forward to checking out your other projects when I have some time.